JP4326706B2 - Circuit board evaluation method, circuit board and manufacturing method thereof - Google Patents

Circuit board evaluation method, circuit board and manufacturing method thereof Download PDF

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Publication number
JP4326706B2
JP4326706B2 JP2001001155A JP2001001155A JP4326706B2 JP 4326706 B2 JP4326706 B2 JP 4326706B2 JP 2001001155 A JP2001001155 A JP 2001001155A JP 2001001155 A JP2001001155 A JP 2001001155A JP 4326706 B2 JP4326706 B2 JP 4326706B2
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Prior art keywords
circuit board
metal
circuit
heat sink
solder
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JP2002207018A (en
Inventor
佳孝 谷口
信行 吉野
好彦 辻村
浩二 西村
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Denka Co Ltd
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Denki Kagaku Kogyo KK
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Description

【0001】
【発明の属する技術分野】
本発明は、半導体素子等の電子部品を搭載したモジュールとして用いられる回路基板に関する。
【0002】
【従来の技術】
半導体素子等の電子部品を搭載したモジュールは、近来のエレクトロニクス技術の発展に伴う高出力化が進む中、達成すべき課題は、電子部品搭載用回路基板の耐久性を高めるとともに、電子部品から発生した熱を効率よく速やかに系外に逃がすため、電子部品から回路基板への熱伝導を阻害する半田ボイドを低減することである。
【0003】
電子部品搭載用回路基板の基本構造は、セラミックス基板の表面に金属回路、裏面に金属放熱板が形成され、該金属回路と金属放熱板にNiめっきが施されている。そして、モジュールの組み立ての際に、金属回路に半導体素子が搭載され、金属放熱板面をベース板に半田付けして固定される。
【0004】
セラミックス基板の材質としては、アルミナ、窒化アルミニウム、窒化ケイ素等、また金属回路、金属放熱板、ベース板の材質としては、銅、アルミニウム、それらの合金等が用いられている。また、セラミックス基板と金属回路、金属放熱板との接合は、Ag、Cu又はAg−Cu合金とTi、Zr、Hf等の活性金属成分を含むろう材を用いる活性金属ろう付け法が主流となっている。
【0005】
回路基板にヒートサイクル等の熱負荷が加わると、セラミックス基板と金属の熱膨張差に起因する熱応力が発生し、セラミックス基板と金属回路、金属放熱板(以下、両者を「金属回路等」という。)の接合端面において、セラミックス基板にクラックが発生する。このクラックは、熱負荷のサイクル数の増加と共に進展し、極端な場合には絶縁破壊に至る。このような、クラックの発生を抑制するため、金属回路の材質として、熱応力が小さいAlが用いられるようになってきている。
【0006】
Al回路と半導体素子(シリコンチップ等)や、Al放熱板とベース板の接合には、Pb−Sn系の半田を用いて行われるため、Al表面にはNiめっきを施す必要がある。金属回路等がCu材質である場合も、酸化防止や半田との反応による信頼性低下を防ぐため、一般的にはNiめっきが施される。半田付けには、フラックスを用いて大気中又は窒素中でリフローする方法と、フラックスを用いないで水素雰囲気下でリフローする方法がある。工程の簡略化と環境問題のためには後者が望ましいが、めっきされたNiと半田のSnとの反応性が良くないので、半田ボイドといわれる空隙が発生し、熱抵抗が増大することが問題となる。
【0007】
これを解決するには、純度の高い電気Niめっき法を採用すればよいが、取り扱いが煩雑となるためにコスト高となるだけでなく、ファインパターンに適用できないことが問題となる。
【0008】
【発明が解決しようとする課題】
本発明の目的は、安価な無電解Niめっきを用いて、電子部品と回路基板との間の半田ボイド率が小さくなる回路基板を提供することである。
【0009】
【課題を解決するための手段】
すなわち、本発明は、次のとおりである。
(請求項1)セラミックス基板の表面に金属回路、裏面に金属放熱板が形成されてなる回路基板の評価方法であって、上記金属回路の表面に、Pb(90%)−Sn(10%)半田片を挟んでシリコンチップを載置し、それを水素雰囲気下、温度150℃までを15〜20℃/minの速度で、その後は2.3〜2.5℃/minの速度で昇温して温度350℃±5℃まで高めた後、速やかに、室温下、自然冷却して半田付けを行い、その半田ボイド率を測定することによって、上記回路基板を用いて組み立てられたモジュールの放熱特性を知ることを特徴とする回路基板の評価方法。
(請求項2)セラミックス基板の表面に金属回路、裏面に金属放熱板が形成され、該金属回路と金属放熱板にNiめっきが施されてなる回路基板であって、請求項1の方法によって測定された半田ボイド率が1.2%よりも小さいものであることを特徴とする回路基板。
(請求項3)セラミックス基板の表面に金属回路、裏面に金属放熱板を形成後、該金属回路と金属放熱板に無電解Niめっきを施した後、1Pa以下の真空中、温度280±10℃で10〜30分熱処理することを特徴とする請求項2記載の回路基板の製造方法。
【0010】
【発明の実施の形態】
以下、更に詳しく本発明を説明する。
【0011】
本発明で用いられるセラミックス基板の材質は、高信頼性及び高絶縁性の点から、窒化アルミニウム又は窒化ケイ素が好ましい。セラミックス基板の厚みは目的によって自由に変えられる。通常は0.635mmであるが、0.5〜0.3mm程度の薄物でもよい。高電圧下での絶縁耐圧を著しく高めたいときには、1〜3mmの厚物が用いられる。
【0012】
金属回路等の材質としては、Al、Cu又はAl−Cu合金であることが好ましい。これらは、単体ないしはこれを一層として含むクラッド等の積層体の形態で用いられる。Alは、Cuよりも降伏応力が小さく、塑性変形に富み、ヒートサイクルなどの熱応力負荷時において、セラミックス基板にかかる熱応力を大幅に低減できるので、Cuよりもセラミックス基板に発生するクラックを抑制することが可能となり、高い信頼性回路基板となる。
【0013】
金属回路の厚みは、電気的、熱的特性の面からAl回路の場合は0.4〜0.5mm、Cu回路は0.3〜0.5mmであることが好ましい。一方、金属放熱板の厚みは、半田付け時の反りを生じさせないように決定される。具体的には、Al放熱板の場合は0.1〜0.4mm、Cu放熱板は0.15〜0.4mmであることが好ましい。
【0014】
セラミックス基板に金属回路等を形成させるには、金属板とセラミックス基板とを接合した後、エッチングする方法、金属板から打ち抜かれた回路及び放熱板のパターンをセラミックス基板に接合する方法等によって、行うことができる。
【0015】
Niめっきが施される前の金属回路等の表面は、研削、物理研磨、化学研磨等によって平滑化されていることが好ましく、表面粗さがRa≦0.2μmであることが好ましい。
【0016】
Niめっきは無電解法が好ましく、これによってファインパターンに対応可能となる。Niめっき膜厚は2〜8μmであることが好ましい。
【0017】
本発明の回路基板は、上記Niめっきの施された回路基板であって、後述する半田ボイド率が1.2%よりも小さいものである。このような回路基板を用いて組み立てられたモジュールの放熱特性は、Niめっき法が無電解法であるにもかかわらず良好となる。
【0018】
本発明の回路基板は、上記Niめっきの施された回路基板を1Pa以下の真空中、温度280±10℃で10〜30分熱処理することによって製造することができる。
【0019】
本発明におけるNiめっきの熱処理は、Niの結晶性を高め半田のSn成分との反応性を高めるために行うものである。1Pa以下の真空中で熱処理することによって、めっき表面の酸化膜が還元され、Sn成分との反応性が向上する。真空度が1Paをこえると、Niめっき面の酸化が著しくなり、Sn成分との反応性が逆に悪化する。一方、熱処理温度が270℃未満ではNiの高結晶性が十分でなく、Sn成分との反応性を目的とするレベルまでに高めることができない。また、290℃超ではNiめっき膜の硬化が起こり、回路基板に損傷を与えてしまう。
【0020】
つぎに、本発明の回路基板の評価方法について説明すると、本発明の評価方法は、金属回路にシリコンチップを特定条件で半田付けしてから半田ボイド率を測定し、その大きさによって、その回路基板が用いられたモジュールの放熱特性を判断するものである。
【0021】
本発明では、金属回路にPb(90%)−Sn(10%)半田片を挟んでシリコンチップを載置する。半田片とシリコンチップの寸法は、底面積5〜25mm2×厚さ0.5〜1.0mmの板が望ましい。
【0022】
半田付けは、水素雰囲気下、温度150℃までを15〜20℃/minの速度で、その後は2.3〜2.5℃/minの速度で昇温して温度350℃±5℃まで高めた後、速やかに室温下で自然冷却することによって行われる。
【0023】
150℃までを15〜20℃/minにて昇温する理由については、15℃/minよりも遅いとNiめっき面が酸化されてしまい、本来の半田濡れ性を正しく評価することができない。また、20℃/minよりも速くするには装置が大がかりとなる。350℃までを2.3〜2.5℃/minにて昇温する理由については、2.3℃/minよりも遅いとNiめっき面が酸化されてしまい、本来の半田濡れ性を正しく評価することができない。2.5℃/minよりも速くすると、半田の溶融が十分でなく、本来の半田濡れ性を正しく評価することができない。
【0024】
半田ボイド率の測定は、軟X線探傷装置又は超音波探傷装置を用いて、自動的に測定することができる。測定装置の市販品をあげれば、例えば、軟X線探傷装置としては、ソフテックス社製「PRO−TEST 100」、超音波探傷装置としては、本多電子社製「HA−701」等である。
【0025】
半田ボイド率が2%を境にして、その回路基板を用いて組み立てられたモジュールの放熱特性が大きく変化する。量産に適用する場合は、試料数10個の平均値+4σの値が2%以下になるよう管理することが望ましい。
【0026】
【実施例】
以下、実施例と比較例をあげて更に具体的に本発明を説明する。
【0027】
実施例1〜4 比較例1〜4 参考例1〜4
0.635mm×58×33mmの窒化アルミニウム基板(熱伝導率170W/mK、3点曲げ強度400MPa)の表面にAl回路形成用Al板(厚み0.4mm、純度>99.9%)を、また裏面にはAl放熱板形成用Al板(厚み0.1mm、純度>99.9%)を、ろう材(Al−Cu(4%)合金箔、厚み30μm)を挟んでホットプレス装置に配置し、温度630℃、3MPaに加圧して接合した。
【0028】
得られた接合体にエッチングレジストを塗布し、FeCl3液でエッチングを行って、端部が縁取りされただけのベタAl回路とベタAl放熱板を有する回路基板を作製した。
【0029】
得られた回路基板に、表1に示す各種条件にて無電解Ni−Pめっき(奥野製薬社製「ニムデンSX」)を施してから熱処理を行い、半田ボイド率を以下に従って測定した。また、上記回路基板を用いて組み立てられたモジュールの放熱特性を以下に従って測定した。それらの結果を表1に示す。
【0030】
(1)半田ボイド率の測定
回路基板の金属回路にPb(90%)−Sn(10%)半田片(底面積169mm2×厚さ0.1mmの板)を挟んでシリコンチップ(底面積169mm2×厚さ0.4mmの板)を載置する。これを、水素雰囲気中、表1に示す各種条件で加熱して半田付けを行い、半田ボイド率を軟X線探傷装置(ソフテックス社製「PRO−TEST 100」)を用いて測定した。
(2)モジュールの放熱特性
図1に示される簡易モジュールに組み立て、シリコンチップへの電力供給量145W、Alヒートシンク温度65℃の条件下、シリコンチップからAl放熱板の間の熱抵抗を測定し、放熱特性を評価した。
【0031】
【表1】

Figure 0004326706
【0032】
表1の実施例1〜3と参考例1〜4との対比から、本発明の評価方法は、信頼性の高いものであることがわかる。また、実施例1〜4及び参考例1〜4と比較例1〜4との対比から、本発明の製造方法によって得られた回路基板を用いて組み立てられたモジュールは、熱抵抗が小さいものであることがわかる。
【0033】
【発明の効果】
本発明によれば、モジュールを組み立てたときの放熱特性を知ることができる回路基板の評価方法が提供される。
【0034】
本発明によれば、放熱特性に優れたモジュールを組み立てることのできる回路基板が提供される。
【0035】
本発明によれば、純度の高い電気Niめっき法によらず、無電解Niめっき法によって、放熱特性に優れたモジュールを組み立てることのできる回路基板の製造方法が提供される。
【図面の簡単な説明】
【図1】放熱特性を測定するための簡易モジュール組立図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit board used as a module on which an electronic component such as a semiconductor element is mounted.
[0002]
[Prior art]
Modules equipped with electronic components such as semiconductor elements are becoming more powerful with the recent development of electronics technology. This is to reduce solder voids that hinder heat conduction from the electronic component to the circuit board in order to efficiently and quickly release the generated heat to the outside of the system.
[0003]
The basic structure of the electronic component mounting circuit board is such that a metal circuit is formed on the surface of the ceramic substrate, a metal heat sink is formed on the back surface, and Ni plating is applied to the metal circuit and the metal heat sink. When the module is assembled, a semiconductor element is mounted on the metal circuit, and the metal heat sink surface is soldered to the base plate and fixed.
[0004]
As the material of the ceramic substrate, alumina, aluminum nitride, silicon nitride, etc., and as the material of the metal circuit, the metal heat sink, and the base plate, copper, aluminum, alloys thereof and the like are used. Also, the active metal brazing method using a brazing material containing an active metal component such as Ti, Zr, Hf and the like is mainly used for joining the ceramic substrate to the metal circuit and the metal heat sink. ing.
[0005]
When a thermal load such as a heat cycle is applied to the circuit board, thermal stress is generated due to the difference in thermal expansion between the ceramic substrate and the metal, and the ceramic substrate, the metal circuit, and the metal heat sink (hereinafter both referred to as “metal circuit etc.”). )) Cracks are generated in the ceramic substrate. This crack progresses with an increase in the number of cycles of the heat load, and in the extreme case, leads to dielectric breakdown. In order to suppress the occurrence of such cracks, Al having a low thermal stress has been used as a material for metal circuits.
[0006]
Since the Al circuit and the semiconductor element (silicon chip or the like) or the Al heat sink and the base plate are joined using Pb—Sn solder, it is necessary to perform Ni plating on the Al surface. Even when the metal circuit or the like is made of a Cu material, Ni plating is generally applied in order to prevent oxidation and deterioration of reliability due to reaction with solder. For soldering, there are a method of reflowing in the air or nitrogen using a flux, and a method of reflowing in a hydrogen atmosphere without using a flux. The latter is desirable for simplification of the process and environmental problems, but the reactivity between the plated Ni and the Sn of the solder is not good, so there is a problem that voids called solder voids are generated and the thermal resistance increases. It becomes.
[0007]
In order to solve this, a high-purity electric Ni plating method may be employed. However, since handling becomes complicated, not only does the cost increase, but there is a problem that it cannot be applied to a fine pattern.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a circuit board in which the solder void ratio between the electronic component and the circuit board is reduced by using inexpensive electroless Ni plating.
[0009]
[Means for Solving the Problems]
That is, the present invention is as follows.
(Claim 1) A circuit board evaluation method in which a metal circuit is formed on the front surface of a ceramic substrate and a metal heat sink is formed on the back surface, wherein Pb (90%)-Sn (10%) is formed on the surface of the metal circuit. A silicon chip is placed with a solder piece in between, and the temperature is increased at a rate of 15 to 20 ° C./min up to a temperature of 150 ° C. in a hydrogen atmosphere, and then at a rate of 2.3 to 2.5 ° C./min. After the temperature is raised to 350 ° C. ± 5 ° C., the module is assembled by using the circuit board by quickly cooling and soldering at room temperature and measuring the solder void ratio. A circuit board evaluation method characterized by knowing characteristics.
(Claim 2) A circuit board in which a metal circuit is formed on the surface of a ceramic substrate, a metal heat sink is formed on the back surface, and Ni plating is applied to the metal circuit and the metal heat sink, and is measured by the method of claim 1. A circuit board having a solder void ratio of less than 1.2%.
(Claim 3) After forming a metal circuit on the surface of the ceramic substrate and a metal heat sink on the back surface, electroless Ni plating is applied to the metal circuit and the metal heat sink, and then a temperature of 280 ± 10 ° C. in a vacuum of 1 Pa or less. The method for manufacturing a circuit board according to claim 2, wherein the heat treatment is performed for 10 to 30 minutes.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0011]
The material of the ceramic substrate used in the present invention is preferably aluminum nitride or silicon nitride from the viewpoint of high reliability and high insulation. The thickness of the ceramic substrate can be freely changed according to the purpose. Usually, it is 0.635 mm, but a thin object of about 0.5 to 0.3 mm may be used. When it is desired to remarkably increase the withstand voltage under high voltage, a thickness of 1 to 3 mm is used.
[0012]
The material for the metal circuit or the like is preferably Al, Cu, or an Al—Cu alloy. These are used in the form of a single body or a laminated body such as a clad including this as a single layer. Al has a lower yield stress than Cu, is rich in plastic deformation, and can significantly reduce the thermal stress applied to the ceramic substrate when subjected to thermal stress such as a heat cycle, thus suppressing cracks generated in the ceramic substrate more than Cu. And a highly reliable circuit board.
[0013]
The thickness of the metal circuit is preferably 0.4 to 0.5 mm in the case of an Al circuit and 0.3 to 0.5 mm in the case of a Cu circuit in terms of electrical and thermal characteristics. On the other hand, the thickness of the metal heat radiating plate is determined so as not to cause warpage during soldering. Specifically, it is preferable that the Al heat sink is 0.1 to 0.4 mm, and the Cu heat sink is 0.15 to 0.4 mm.
[0014]
A metal circuit or the like is formed on a ceramic substrate by bonding a metal plate and a ceramic substrate and then etching, or a method of bonding a circuit punched from a metal plate and a pattern of a heat sink to the ceramic substrate. be able to.
[0015]
The surface of the metal circuit or the like before being subjected to Ni plating is preferably smoothed by grinding, physical polishing, chemical polishing or the like, and the surface roughness is preferably Ra ≦ 0.2 μm.
[0016]
The Ni plating is preferably an electroless method, which makes it possible to handle fine patterns. The Ni plating film thickness is preferably 2 to 8 μm.
[0017]
The circuit board of the present invention is a circuit board on which the above-described Ni plating is applied, and has a solder void ratio described below of less than 1.2%. The heat dissipation characteristics of a module assembled using such a circuit board are good even though the Ni plating method is an electroless method.
[0018]
The circuit board of the present invention can be produced by heat-treating the Ni-plated circuit board in a vacuum of 1 Pa or less at a temperature of 280 ± 10 ° C. for 10 to 30 minutes.
[0019]
The heat treatment of Ni plating in the present invention is performed in order to increase the crystallinity of Ni and increase the reactivity with the Sn component of the solder. By performing the heat treatment in a vacuum of 1 Pa or less, the oxide film on the plating surface is reduced and the reactivity with the Sn component is improved. When the degree of vacuum exceeds 1 Pa, oxidation of the Ni plating surface becomes remarkable, and the reactivity with the Sn component deteriorates conversely. On the other hand, if the heat treatment temperature is less than 270 ° C., the high crystallinity of Ni is not sufficient, and the reactivity with the Sn component cannot be increased to the target level. On the other hand, if it exceeds 290 ° C., the Ni plating film is hardened and the circuit board is damaged.
[0020]
Next, a method for evaluating a circuit board according to the present invention will be described. The evaluation method according to the present invention measures a solder void ratio after soldering a silicon chip to a metal circuit under a specific condition, and determines the circuit according to the size. This is to determine the heat dissipation characteristics of the module in which the substrate is used.
[0021]
In the present invention, a silicon chip is placed with a Pb (90%)-Sn (10%) solder piece sandwiched between metal circuits. As for the size of the solder pieces and the silicon chip, a plate having a bottom area of 5 to 25 mm 2 × thickness of 0.5 to 1.0 mm is desirable.
[0022]
Soldering is performed at a temperature of 15 to 20 ° C./min up to a temperature of 150 ° C. in a hydrogen atmosphere, and then raised to a temperature of 350 ° C. ± 5 ° C. at a rate of 2.3 to 2.5 ° C./min. After that, it is carried out by natural cooling immediately at room temperature.
[0023]
Regarding the reason for raising the temperature up to 150 ° C. at 15 to 20 ° C./min, if it is slower than 15 ° C./min, the Ni plating surface is oxidized, and the original solder wettability cannot be correctly evaluated. Moreover, the apparatus becomes a large scale in order to make it faster than 20 ° C./min. Regarding the reason for raising the temperature up to 350 ° C. at 2.3 to 2.5 ° C./min, if it is slower than 2.3 ° C./min, the Ni plating surface is oxidized, and the original solder wettability is correctly evaluated. Can not do it. If it is faster than 2.5 ° C./min, the solder is not sufficiently melted and the original solder wettability cannot be correctly evaluated.
[0024]
The solder void ratio can be automatically measured using a soft X-ray flaw detector or an ultrasonic flaw detector. For example, a soft X-ray flaw detector is “PRO-TEST 100” manufactured by Softex Corporation, and an ultrasonic flaw detector is “HA-701” manufactured by Honda Electronics Co., Ltd. .
[0025]
When the solder void ratio is 2%, the heat dissipation characteristic of the module assembled using the circuit board changes greatly. When applied to mass production, it is desirable to manage so that the average value of 4 samples + 4σ is 2% or less.
[0026]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
[0027]
Examples 1-4 Comparative Examples 1-4 Reference Examples 1-4
An Al circuit forming Al plate (thickness 0.4 mm, purity> 99.9%) on the surface of a 0.635 mm × 58 × 33 mm aluminum nitride substrate (thermal conductivity 170 W / mK, three-point bending strength 400 MPa) On the back side, an Al heat sink forming Al plate (thickness 0.1 mm, purity> 99.9%) is placed in a hot press apparatus with a brazing material (Al—Cu (4%) alloy foil, thickness 30 μm) sandwiched between them. The temperature was 630 ° C., and the pressure was increased to 3 MPa to join.
[0028]
An etching resist was applied to the obtained joined body, and etching was performed with an FeCl 3 solution, so that a circuit board having a solid Al circuit and a solid Al heat dissipation plate whose edges were just edged was manufactured.
[0029]
The obtained circuit board was subjected to electroless Ni—P plating (“Nimden SX” manufactured by Okuno Pharmaceutical Co., Ltd.) under various conditions shown in Table 1, followed by heat treatment, and the solder void ratio was measured as follows. Moreover, the heat dissipation characteristic of the module assembled using the said circuit board was measured according to the following. The results are shown in Table 1.
[0030]
(1) Measurement of Solder Void Ratio A silicon chip (bottom area 169 mm) with a Pb (90%)-Sn (10%) solder piece (bottom area 169 mm 2 × thickness 0.1 mm plate) sandwiched between metal circuits of a circuit board 2 × plate having a thickness of 0.4 mm). This was heated and soldered in various conditions shown in Table 1 in a hydrogen atmosphere, and the solder void ratio was measured using a soft X-ray flaw detector (“PRO-TEST 100” manufactured by Softex).
(2) Heat dissipation characteristics of the module Assembled into the simple module shown in Fig. 1, measured the thermal resistance between the silicon chip and the Al heat sink under the condition of 145W power supply to the silicon chip and Al heat sink temperature of 65 ° C, heat dissipation characteristics Was evaluated.
[0031]
[Table 1]
Figure 0004326706
[0032]
From the comparison between Examples 1 to 3 and Reference Examples 1 to 4 in Table 1, it can be seen that the evaluation method of the present invention is highly reliable. Moreover, the module assembled using the circuit board obtained by the manufacturing method of this invention from the contrast with Examples 1-4 and Reference Examples 1-4 and Comparative Examples 1-4 has a small thermal resistance. I know that there is.
[0033]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the evaluation method of the circuit board which can know the thermal radiation characteristic when a module is assembled is provided.
[0034]
ADVANTAGE OF THE INVENTION According to this invention, the circuit board which can assemble the module excellent in the thermal radiation characteristic is provided.
[0035]
ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the circuit board which can assemble the module excellent in the heat dissipation characteristic by the electroless Ni plating method is provided instead of the high-purity electric Ni plating method.
[Brief description of the drawings]
FIG. 1 is a simplified module assembly diagram for measuring heat dissipation characteristics.

Claims (3)

セラミックス基板の表面に金属回路、裏面に金属放熱板が形成されてなる回路基板の評価方法であって、上記金属回路の表面に、Pb(90%)−Sn(10%)半田片を挟んでシリコンチップを載置し、それを水素雰囲気下、温度150℃までを15〜20℃/minの速度で、その後は2.3〜2.5℃/minの速度で昇温して温度350℃±5℃まで高めた後、速やかに、室温下、自然冷却して半田付けを行い、その半田ボイド率を測定することによって、上記回路基板を用いて組み立てられたモジュールの放熱特性を知ることを特徴とする回路基板の評価方法。 A method for evaluating a circuit board in which a metal circuit is formed on the surface of a ceramic substrate and a metal heat sink is formed on the back surface, and a Pb (90%)-Sn (10%) solder piece is sandwiched between the surfaces of the metal circuit. A silicon chip is placed, and the temperature is raised at a rate of 15 to 20 ° C./min up to a temperature of 150 ° C. in a hydrogen atmosphere. After raising the temperature to ± 5 ° C, quickly cool it at room temperature and solder it, and measure the solder void ratio to know the heat dissipation characteristics of the module assembled using the circuit board. A method for evaluating a characteristic circuit board. セラミックス基板の表面に金属回路、裏面に金属放熱板が形成され、該金属回路と金属放熱板に無電解Niめっきが施されてなる回路基板であって、請求項1の方法によって測定された半田ボイド率が1.2%よりも小さいものであることを特徴とする回路基板。A circuit board comprising a ceramic circuit board having a metal circuit formed on the front surface and a metal heat sink formed on the back surface, the electroless Ni plating being applied to the metal circuit and the metal heat sink, and the solder measured by the method of claim 1 A circuit board having a void ratio smaller than 1.2%. セラミックス基板の表面に金属回路、裏面に金属放熱板を形成後、該金属回路と金属放熱板に無電解Niめっきを施した後、1Pa以下の真空中、温度280±10℃で10〜30分熱処理することを特徴とする請求項2記載の回路基板の製造方法。 After forming a metal circuit on the surface of the ceramic substrate and a metal heat sink on the back surface, electroless Ni plating is applied to the metal circuit and the metal heat sink, and then at a temperature of 280 ± 10 ° C. for 10 to 30 minutes in a vacuum of 1 Pa or less. The method of manufacturing a circuit board according to claim 2, wherein heat treatment is performed.
JP2001001155A 2001-01-09 2001-01-09 Circuit board evaluation method, circuit board and manufacturing method thereof Expired - Fee Related JP4326706B2 (en)

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